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P2-113 Evaluation of a Real-time PCR Assay for the Detection of Genus Listeria

Tuesday, August 5, 2014
Exhibit Hall D (Indiana Convention Center)
Timothy Dambaugh, DuPont Nutrition & Health, Wilmington, DE
Seth Blumerman, DuPont Nutrition & Health, Wilmington, DE
Mark Jensen, DuPont Nutrition & Health, Wilmington, DE
Daniel DeMarco, DuPont Nutrition & Health, Wilmington, DE
Stephen Varkey, DuPont Nutrition & Health, Wilmington, DE
Teresa Brodeur, DuPont Nutrition & Health, Wilmington, DE
Bridget Andaloro, DuPont Nutrition & Health, Wilmington, DE
Dawn Fallon, DuPont Nutrition & Health, Wilmington, DE
Morgan Wallace, DuPont Nutrition & Health, Wilmington, DE
Lois Fleck, DuPont Nutrition & Health, Wilmington, DE
Andrew Farnum, DuPont Nutrition & Health, Wilmington, DE
George Tice, DuPont Nutrition & Health, Wilmington, DE
Introduction: Rapid screening methods for Listeria species can assess potential risk of Listeria monocytogenes contamination of foods and the efficacy of environmental cleaning and disinfection. PCR screening methods provide sensitivity, specificity, ease of use and faster time-to-result relative to standard cultural methods.

Purpose: This study evaluates the new DuPont™ BAX® System Real-Time PCR Assay for Genus Listeria, which utilizes shorter lysis protocol and faster processing times than current BAX® System assays for Listeria. Assay sensitivity, inclusivity and exclusivity were assessed in pure culture and in food and environmental surface enrichments relative to standard methods.

Methods: Inclusivity was evaluated by processing 77 different Listeria strains serially diluted to approximately 105 CFU/ml, which is 1-log above the sensitivity limit of the assay. Exclusivity was tested with pure cultures of 75 different non-Listeria strains at ≥108 CFU/ml.  For each of six different food and environmental surfaces, 5 high-spike, 20 low-spike and 5 un-spiked samples were tested with the PCR method after enrichment in proprietary 24LEB Complete, and results were compared to independent spiked samples enriched in BLEB or UVM as appropriate.

Results: For the strains tested, the assay demonstrated 100% inclusivity and 100% exclusivity. No statistical difference was observed in the number of positive spiked food and environmental surface enrichments detected by PCR relative to the standard enrichment and confirmation protocols.

Significance: This new assay allows for a more rapid time-to-result for the testing of food and environmental samples than standard methods, while maintaining the simplicity, accuracy and reliability of the BAX® System.

Back to: Poster Session - Pathogens, Epidemiology, Novel Laboratory Methods, Food Defense, Communication Outreach and Education, General Microbiology, Dairy and Other Food Commodities, Food Toxicology
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